Re: [Buildroot] [PATCH] board/broadcom: add support for Northstar platform devices

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

Hello Rafał,

Thanks for this proposal!

On Tue, 10 Aug 2021 15:12:36 +0200
Rafał Miłecki <zajec5@gmail.com> wrote:

> From: Rafał Miłecki <rafal@milecki.pl>
> 
> Broadcom Northstar family of SoCs is most commonly used for home
> routers. It's an ARM platform with Cortex-A9 CPU(s).
> 
> All known Northstar devices come with CFE bootloader which almost always
> expects a TRX firmware format (with exception for the D-Link). Some
> vendors (like Luxul and Netgear) wrap TRX in their own containers.
> 
> For above reason a plain kernel and rootfs are useless for flashing
> purposes. CFE requires TRX(-like) format and there isn't any CFE
> replacement. Another issue is lack for DTS support in CFE.
> That's why for this board there is post-image script building device
> specific images. It takes care of appending DTB to the kernel and
> putting everything in a TRX image.

Is this also the reason why an initramfs is used, instead of a separated
rootfs?

> board/broadcom/ns/linux.config                | 115 ++++++++++++++++++
> board/broadcom/ns/post-image.sh               |  43 +++++++
> .../ns/rootfs_overlay/etc/init.d/S39network   |   6 +
> .../etc/network/interfaces.luxul,xap-1610-v1  |  24 ++++
> .../etc/network/interfaces.luxul,xwr-3150-v1  |  49 ++++++++
> .../etc/network/interfaces.smartrg,sr400ac    |  49 ++++++++
> configs/broadcom_ns_defconfig                 |  22 ++++
> 7 files changed, 308 insertions(+)

We also need board/broadcom/ns/readme.txt that explains how to use this
defconfig (see other readme.txt files in board/). And we also need an
update to the DEVELOPERS file to associate you with this defconfig and
board/broadcom/ns/ folder.

> diff --git a/board/broadcom/ns/linux.config b/board/broadcom/ns/linux.config
> new file mode 100644
> index 0000000000..1737e1d81a
> --- /dev/null
> +++ b/board/broadcom/ns/linux.config
> @@ -0,0 +1,115 @@
> +CONFIG_KERNEL_XZ=y
> +CONFIG_BLK_DEV_INITRD=y
> +CONFIG_INITRAMFS_SOURCE="${BR_BINARIES_DIR}/rootfs.cpio"

This should not be needed, as it's added by Buildroot.


> diff --git a/board/broadcom/ns/post-image.sh b/board/broadcom/ns/post-image.sh
> new file mode 100755
> index 0000000000..34856991a6
> --- /dev/null
> +++ b/board/broadcom/ns/post-image.sh
> @@ -0,0 +1,43 @@
> +#!/bin/sh
> +
> +# $1: images directory path
> +# $2: device dts filename
> +# $3: board id
> +build_lxl() {
> +	local images="$1"
> +	local device="$2"
> +	local board="$3"
> +
> +	lzma-alone e $images/zImage.$device $images/zImage.$device.lzma -d16

I don't have lzma-alone on my system, so it means that this tool should
probably be built by a Buildroot host package, as it's not necessarily
installed on the developer machine.

> +	rm -f $images/zImage.$device
> +	$HOST_DIR/bin/otrx create $images/$device.trx -f $images/zImage.$device.lzma
> +	rm -f $images/zImage.$device.lzma
> +	$HOST_DIR/bin/lxlfw create $images/$device.lxl -i $images/$device.trx -b "$board"
> +}
> +
> +# $1: images directory path
> +# $2: device dts filename
> +build_trx() {
> +	local images="$1"
> +	local device="$2"
> +
> +	lzma-alone e $images/zImage.$device $images/zImage.$device.lzma -d16
> +	rm -f $images/zImage.$device
> +	$HOST_DIR/bin/otrx create $images/$device.trx -f $images/zImage.$device.lzma
> +	rm -f $images/zImage.$device.lzma
> +}
> +
> +devices="$(sed -n 's/^BR2_LINUX_KERNEL_INTREE_DTS_NAME="\([a-z0-9 \-]*\)"$/\1/p' ${BR2_CONFIG})"
> +for device in $devices; do
> +	case "$device" in
> +		"bcm4708-smartrg-sr400ac")
> +			build_trx "$1" "$device"
> +			;;
> +		"bcm47094-luxul-xap-1610")
> +			build_lxl "$1" "$device" "XAP-1610"
> +			;;
> +		"bcm47094-luxul-xwr-3150-v1")
> +			build_lxl "$1" "$device" "XWR-3150"
> +			;;
> +	esac
> +done

Hm, so this defconfig in fact targets a family of devices. Buildroot
defconfigs normally target a single device. But I see the point here,
so perhaps we should leave it as you propose.

> diff --git a/board/broadcom/ns/rootfs_overlay/etc/init.d/S39network b/board/broadcom/ns/rootfs_overlay/etc/init.d/S39network
> new file mode 100755
> index 0000000000..a8098d2ab4
> --- /dev/null
> +++ b/board/broadcom/ns/rootfs_overlay/etc/init.d/S39network
> @@ -0,0 +1,6 @@
> +#!/bin/sh
> +
> +machine="$(cat /proc/device-tree/compatible | tr '\0' '\t' | cut -f 1)"
> +
> +interfaces="/usr/local/etc/network/interfaces.$machine"
> +[ -f "$interfaces" ] && cp "$interfaces" /etc/network/interfaces
> diff --git a/board/broadcom/ns/rootfs_overlay/usr/local/etc/network/interfaces.luxul,xap-1610-v1 b/board/broadcom/ns/rootfs_overlay/usr/local/etc/network/interfaces.luxul,xap-1610-v1
> new file mode 100644
> index 0000000000..bf766044b4
> --- /dev/null
> +++ b/board/broadcom/ns/rootfs_overlay/usr/local/etc/network/interfaces.luxul,xap-1610-v1

[...]

> diff --git a/board/broadcom/ns/rootfs_overlay/usr/local/etc/network/interfaces.luxul,xwr-3150-v1 b/board/broadcom/ns/rootfs_overlay/usr/local/etc/network/interfaces.luxul,xwr-3150-v1

[...]

> diff --git a/board/broadcom/ns/rootfs_overlay/usr/local/etc/network/interfaces.smartrg,sr400ac b/board/broadcom/ns/rootfs_overlay/usr/local/etc/network/interfaces.smartrg,sr400ac

I am not sure how much we want those quite specific network
configuration files in Buildroot itself. Shouldn't we leave that up to
the user? Those example files use 0.0.0.0 as a static IP address for
all interfaces, which isn't going to be very useful in practice I guess.

> diff --git a/configs/broadcom_ns_defconfig b/configs/broadcom_ns_defconfig
> new file mode 100644
> index 0000000000..b68de2e093
> --- /dev/null
> +++ b/configs/broadcom_ns_defconfig
> @@ -0,0 +1,22 @@
> +BR2_arm=y
> +BR2_cortex_a9=y
> +BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_10=y
> +BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_MDEV=y

Needed for ?

> +BR2_ROOTFS_OVERLAY="board/broadcom/ns/rootfs_overlay"
> +BR2_ROOTFS_POST_IMAGE_SCRIPT="board/broadcom/ns/post-image.sh"
> +BR2_LINUX_KERNEL=y
> +BR2_LINUX_KERNEL_CUSTOM_VERSION=y
> +BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="5.10.57"
> +BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
> +BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/broadcom/ns/linux.config"
> +BR2_LINUX_KERNEL_APPENDED_ZIMAGE=y
> +BR2_LINUX_KERNEL_XZ=y
> +BR2_LINUX_KERNEL_INTREE_DTS_NAME="bcm4708-smartrg-sr400ac bcm47094-luxul-xap-1610 bcm47094-luxul-xwr-3150-v1"
> +BR2_PACKAGE_MTD=y

Not needed.

> +BR2_PACKAGE_LINUX_FIRMWARE=y
> +BR2_PACKAGE_LINUX_FIRMWARE_BRCM_BCM4366C0=y
> +BR2_PACKAGE_BRIDGE_UTILS=y

Most likely not needed if we drop the network configuration files.

> +BR2_PACKAGE_DROPBEAR=y

Not needed (we want defconfigs to be minimal)

> +BR2_TARGET_ROOTFS_INITRAMFS=y
> +# BR2_TARGET_ROOTFS_TAR is not set
> +BR2_PACKAGE_HOST_FIRMWARE_UTILS=y

Thanks!

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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